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Nablus tower is a multi storey building of 21 stories. These stories produce heavy loads above the soil. This building is relatively heavy if we compared it with the ordinary buildings in the city which almost do not exceed 12 or 13 stories each. So the design of the footing will be more critical and needs special care and attention . Introduction
This tower is the first tower in Nablus city and in the north of West Bank. It lies in Rafeedia main street to the west of Nablus The height of the tower is 80 meters . The area of the first 15 stories is 990m2 And the area for the last 6 stories is 530 m2
1- Select the most appropriate types of foundations for the project. 2- Design the selected footings. 3- Calculate the settlement. 4- Estimate costs of the foundations designed. Scope of the project
The weights of the whole structure were calculated by using the Tributary area method ,then we have found the loads on each column. Total load of the whole structure = Loads from first 15 stories + last 6 = 28531 + 6100 = 34631 ton. Structural Analysis
After calculating the loads on each column, we have decided to use PILE FOUNDATION SYSTEM due to the heavy loads existed, the soil bearing capacity is medium, so this had led us also to use this system.In this design we made many iterations to achieve the perfect design. Using one pile or two piles in one cap is not preferred because of the instability in this case, so we have tried to use 5 piles in one cap or more depending on the loads on each column. Design of footings
Number of piles in the one cap was restricted by the geometry of the whole system. The over lapping between piles was the main reason in this case. The minimum distance between two piles was 2.5 the diameter of the pile So the loads and the minimum distance between two piles were the two main factors in the design. The diameter of the pile is 100 cm and it is the same in every pile, also we tried in this case to achieve practical design.
The footing under the shear walls area was designed in a different way. Due to the heavy loads and the limited area, piles are not chosen. We have designed it as MAT FOUNDATION. The area of mat foundation is approximately 180 m2
The design of the piles was done by ALL PILE program. Pile Design
As = ρ X area = 0.005 (π/4)(1000)2 = 3927 mm 2 Use 15 Ф 18 It is recommended to use spiral stirrups 1Ф8 mm / 10 cm . Design of Reinforcement in the Piles :
Moments are not uniformly distributed , so there were no column strips nor middle strip . We divided the mat into several parts .Then we read the maximum moment in each part, and the reinforcement calculated was depending on this reading .
Reinforcement in mat Foundation X - direction
The dimensions were suggested to be 40*70 cm as below As = ρ * b * d = (0.0033)(400)(640) = 844.8 mm2 use 5Ø16 bottom steel. use 5Ø16 top steel. cover = 6cm . Design of grade beams (Av/s) = Min ((3.5 bw/fy) , (0.2 bw /fy)) (Av/s) = 0.033. use 1Ø10/30 cm
In order to estimate the total cost we have to calculate the concrete cost , the steel costs, and the cost of drilling the piles . Concrete costs based on size calculations . Steel costs based on weight calculations. Drilling costs based on lengths costs (the diameter is constant) cost Estimation
The total cost of concrete = 3152*320 = 1008640 Total cost of steel= 112*3300 = 369600 NIS Cost of the drilling = 2690*50 = 134500 NIS Total cost of the concrete , steel , and drilling = 1008650+369600+134500 = 1,512,750 NIS. ≈ 1.513.000 NIS
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